Container with pre-incised tear strip



Aug. 8, 1967 G. F. SMYTH 3,334,777

CONTAINER WITH PRE-INCISED TEAR STRIP Filed June 16, 1965 2 Sheets-Sheet l INVENTUR. ea/ye F Aug. 8, 1967 G. F. SMYTH 3,334,777

CONTAINER WITH FRE-INCISED TEAFI STRIP Filed June 16, 1965 2 Sheets-Sheet f IN VENTOR.

United States Patent 3,334,777 CONTAINER WITH PRE-INCISED TEAR STRIP George F. Smyth, Los Angeles, Calif., assignor, by mesne assignments, to Erma] C. Fraze, Dayton, Ohio Filed June 16, 1965, Ser. No. 464,385 13 Claims. (Cl. 22054) ABSTRACT OF THE DISCLOSURE A tear stn'p formed by a line of scoring in a can top is provided with a tab to serve as manual means to sever the tear strip. To facilitate initial severance, the can top is incised at a point on the line of scoring and the incision is covered by a sealant. The can top is scored and incised in one operation and in the finished can top the incision is directly under the peripheral bead of a hollow rivet that attaches the tab to the tear strip.

This invention relates to an easy opening container of the type in which the sheet material of a wall of the container is weakened along a score line to define a tear strip and a tab is attached to the tear strip to serve as a handle for use in severing the tear strip. The invention is directed specifically to the problem of minimizing the effort required to sever the tear strip.

The manual force required to open a container of this type depends, on the one hand, upon the efi'iciency of the tab as a tool for applying force, and on the other hand, depends upon the resistance to severance of the sheet material.

It has been heretofore suggested that the force-applying efiiciency of a tab may be increased in various ways. For example the tab may be designed for lever action with a high mechanical advantage and in addition the lever may be designed for delayed force application to permit the lever to be lifted to a favorable angle for initiating sever auce of the tear strip. A further suggestion is to combine a desirable cam action with the lever action.

On the other hand, it has been further suggested heretofore that the resistance to the severance of the tear strip may be reduced by employing a new kind of scoring which may be termed extrusion scoring. Extrusion scoring may be employed not only to form a thinner residual web along the score line than heretofore possible, but also may be employed to form an extruded rib on the side of the severance line that lies outside of the area of the tear strip. Such an extruded rib protruding from the inner face of the sheet material resists flex'ure of the sheet material im mediately adjacent the tear strip and thus concentrates stresses to facilitate severance of the sheet material.

Even with all of the improvements that have been made to increase the efliciency of the tab and even with the im proved method of scoring, there is still need for reducing the effort that is required to remove a tear strip. Once the severance of a tear strip is initiated, the tear strip may be peeled away with only moderate effort, the basic difficulty being that a peak force is required to make the start. The present invention meets this basic difiiculty by, in effect, initiating the severance of the tear strip in advance. For this purpose, a preliminary incision is made at a suitable point on the score line in the course of fabricating the container. At the same time a sealant is applied to the region of initial incision. Thus the purchaser is required merely to continue the severance of the tear strip from the region of the initial incision.

A further feature of the invention is that the residual web of metal along the score line that must be severed by the purchaser is initially exceedingly thin and only gradually increases the distance away from the pre-incised 3,334,777 Patented Aug. 8, 1967 ICC region. This fact makes it easy for the purchaser to start the additional severance of the metal beyond the pre-incised region and is especially advantageous because the tab is initially flat against the container wall to make it awkward to apply high initial force to the tear strip.

Along with the basic concept of making a preliminary incision in the sheet material along a minor portion of the score line at the leading end of the tear strip, the invention teaches how the preliminary step may be incorporated in the fabrication of the container at no additional expense and further teaches how the region of the preliminary incision may be sealed against leakage.

Added cost for making the preliminary cut is avoided simply by modifying the scoring dies to make it possible to score and partially shear the container Wall in the same operation. For this purpose the invention takes advantage of the fact that extrusion scoring makes it possible to score to any depth desired without excessive stressing of the residual web that is left by the scoring. In the preferred practice of the invention, the scoring dies are modified to serve as shearing dies along a minute portion of the score line and the residual web progressively tapers in thickness towards that portion in both directions along the score line. The extrusion scoring has the usual further advantage of producing the previously mentioned extruded rib to facilitate the final severance operation.

For the purpose of sealing the preliminary incision in the line of scoring, the invention takes advantage of the fact that extrusion scoring results in a groove that is both relatively wide and relatively deep. The greater width of the scored groove provides an adequate area of contact of sealant with the metal as required for adequate adherence of the sealant. At the same time the greater depth of the groove not only increases the area of adherence but also makes it possible for the groove to contain sealant of sutficient thickness to withstand high fluid pressure in' the container.

With reference to sealing the preliminary incision in the line of scoring, a further feature of the invention is the concept of employing the tab not only as means to protect the sealant but also as means to confine the sealant in the groove for further effectiveness against internal fluid pressure. In the preferred practice of the invention, the tab is anchored by a hollow rivet that is formed in the tear strip, the rivet extending through an aperture in the tab and being formed with a peripheral bead in overhanging engagement with the rim of the aperture, The pre-incised region of the line of scoring is beneath the tab immediately adjacent the aperture of the tab and is directly under the overhanging bead of the rivet. Thus the bead of the rivet clamps the tab against the sealant in the scored groove and adds its strength to the tab in this region.

As will be explained, a further feature of the invention is the offsetting of the pre-incised edges of metal to form a gap into which the sealant may be extruded to form a sealing plug, the gap being so formed as to place the plug beneath the tear strip. In such an arrangement the tear strip may be peeled away from the gap without necessity for the tear strip to shear the sealant plug.

The features and advantages of the invention may be understood from the following description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative FIG. 1 is a plan View of a can top constructed in accordance With the teachings of the invention;

FIG. 2 is a fragmentary sectional view showing how dies may be used to produce a dimple in the can top as a step preliminary to the forming of a hollow rivet for securing a tab to the tear strip;

FIG. 3 is a similar fragmentary section on a larger scale showing how dies may be employed to convert the dimple into a hollow rivet and at the same time not only score thesheet material to form the tear strip but also to shear the sheet material along a minute portion of the line of scoring;

FIG. 4 is a fragmentary sectional view showing how the hollow rivet may be positioned in the aperture of the tab after sealant is applied to the pre-sheared region of the line of scoring;

FIG. 5 is a fragmentary sectional View similar to FIG. 4 showing the hollow rivet staked into permanent overhanging engagement with the rim of the aperture of the tab;

FIG. 6 is a view as seen along the line 66 of FIG. 5 showing the hollow rivet in section and showing the adjacent region of the can top in plan;

FIG. 7 is a greatly enlarged fragmentary sectional view taken along a concentric arc that is indicated at 7-7 in FIG. 6 to show how the thin residual web along the score line tapers in both directions towards the minute portion that is pre-sheared;

FIG. 8 is a fragmentary sectional view on a still larger scale taken as indicated by the line 88 of FIG. 7 showing how the residual web is offset on opposite sides of the shear line to form a gap and further showing how the sealant material forms an extruded sealing plug in the gap;

FIG. 9 is a similarly enlarged fragmentary sectional view taken along the line 9-9 of FIG. 6 to show the cross sectional configuration of the portion of the score line groove that is filled with the sealant and also to show the extruded rib that is created by displacing the metal to form the scored groove; and

FIG. 10 is a similarly enlarged fragmentary sectional view showing the portion of the scoring dies that carries out the pre-shearing operation.

FIG. 1 shows a can top, generally designated 10, which may be made of any suitable material such as an aluminum alloy and which is formed in the usual manner with a rim flange 12 for joining the can top to a cylindrical can body (not shown) in a well known manner. The can top 10 is formed with a line of grooved scoring 14 to define a tear strip, generally designated 15, that may be manually removed to form a corresponding opening in the can top. In this particular embodiment, the tear strip 15 extends generally around the circumference of the can so that severance of the tear strip substantially removes the entire can top.

The grooved scoring 14 that defines the tear strip 15 is produced in accord with the teaching of the invention to minimize initial resistance to severance of the tear strip. A tab 16 of any suitable construction and configuration may be attached in any suitable manner to the leading end of the tear strip to serve as a handle for manipulation of the tear strip. In this particular embodiment of the invention the tab 16 is attached to the tear strip 15 by means of a hollow rivet 18 that is formed in the metal of the tear strip and extends through a corresponding aperture in the tab in positive overlapping engagement with the rim of the aperture.

As shown in FIG. 6, the line of grooved scoring 14 may be divided into two portions, namely, a portion 140 which extends around the leading end of the tear strip, i.e., around three sides of the hollow rivet 18, and a portion 14b of major length which extends around the rest of the tear strip. The portion 14b of the line of grooved scoring is conventional scoring which is produced in a well known manner but the portion 14a of the line of grooved scoring is an example of the heretofore mentioned extrusion scoring which, as will be explained later, is produced by the dies shown in FIGS. 3 and 10. 1

In the preferred practice of the invention it is contemplated that in accord with a well known procedure a rela- 4 tively large dimple, designated 20 in FIG. 2, will be formed in the can top 10 in the region of the desired location of the hollow rivet 18 and subsequently the dimple will be converted into the hollow rivet. To form the dimple, the sheet metal of the can top 10 is processed by die character shown in FIG. 2.

In FIG. 2 an upper annular die 22 is formed with a central cavity 24 and cooperates witha lower male die 25, the lower male die being surrounded by an annular pressure pad 26 that is supported by suitable springs 28. When the die means shown in FIG. 2 closes on the sheet metal, the male die 25 ofisets the sheet metal upward into the cavity 24 and the pressure pad 26 cooperates with the upper die 22 to hold the sheet metal under relatively light pressure to permit the sheet metal to slip radially inwardly for minimum thinning of the sheet metal that forms the dimple.

The dimple 20 is then converted into a rivet 18a of a preliminary configuration, i.e., a configuration in preparation for the final preliminary rivet configuration 18a and FIG. 3 shows the die means for converting the dimple 20 to the final staked rivet configuration shown at 18 in FIGS. 1 and 6. The die means shown in FIG. 3 may be termed a triplepurpose die means since it not only forms the dimple 20 to the preliminary rivet configuration 18a but also forms the entire grooved scoring 14 and at the same time pre-shears the sheet metal along a minute portion of the line of scoring for the basic purpose of the invention.

The die means shown in FIG. 3 comprises a lower. die, generally designated 30, and a cooperating upper die, generally designated 32. As shown in FIG. 3, the upper 'die 32 has a downwardly facing forming cavity-34 with a vent 35 to avoid trapping air and the lower die 30 is formed with a boss 36 that conforms in shape to the inside configuration of the desired hollow rivet. When the lower die 30 enters the cavity 34 it converts the previously mentioned dimple 20 into the desired preliminary rivet configuration, the preformed dimple providing ample metal to make the wall of the rivet relatively thick. As indicated in FIG. 3 there is ample clearance 38 in the cavity 34 to permit thickening of the metal in forming the transverse end wall 39 of the preliminary configuration of the hollow rivet.

The lower die 30 that is formed with the boss 36 has a flat or planar support surface throughout the region of the intended location of the conventional POI,

tion 14b of the line of grooved scoring 14, this flat support surface being designated 40 in FIG. 3. In the region of the desired location of the extrusion scoring 14a, however, the lower die 30 is formed with an elongated recess that conforms to the pattern of the desired extrusion scoring 14a, this recess being designated 42 in FIG. 3.

The upper die 32 has a downwardly protruding continuous scoring element, a longitudinal portion 44 of which corresponds to the portion 14a of the grooved scoring 14 is shaped to result in so-called extrusion scoring, the remainder of the downwardly protruding scoring element being conventional to produce the conventional portion 14b of the grooved scoring 14.

As shown in FIGS. 3, 9 and 10, the configuration of the portion 44 of the continuous scoring element of the upper die 32 and the configuration of the corresponding recess 42 in the lower die 30 are such as to cooperate to produce a line of grooved scoring that in cross section consists of a thin residual web 45, a solid extruded rib 46 to one side of the residual web and a thicker web 48 which connects the rib directly to the can top outside of the area of the tear strip.

It is apparent that the thickness of the residual web 45 depends upon the extent of downward movement of the scoring element 44 of the upper die relative to the lower die 30. If the scoring element 44 moves downward to the position shown in FIG. 10 the residual web 45 disappears and, instead, the two dies cooperate to shear staking operation. FIG. 4 shows thethe sheet metal. In the preferred practice of the invention the scoring element 44 of the upper die is shaped to make relatively deep penetration of the sheet metal in the region where the preliminary incision of the sheet metal is desired. The configuration of the scoring element 44 in this respect is such that the penetration of the scoring element when the two dies close together forms the residual web 45 to the configuration that is shown in cross section in FIG. 7. It can be seen in FIG. 7 that the residual web 45 tapers in both directions towards a shearing zone 50 where the residual web tapers to zero thickness and the scoring element shears the metal along a shear line of minute length, say a length of .002 inch. The scoring element 44 not only shears the sheet metal in this region but also offsets the sheet metal downward on one side of the shear line to produce a gap which is indicated at '52 in FIG. 8.

After the die operation shown in FIG. 3 forms the hollow rivet to the initial configuration 18a and at the same time not only forms the grooved scoring 14 but also makes the desired preliminary incision, the portion 14a of the grooved scoring is filled with a suitable sealant 54, the sealant being shown in plan in FIG. 6 and in cross section in FIG. 9. It will be noted in FIG. 9 that the sealant 54 is substantially flush with the top of the scoring groove. The sealant may be a conventional plastisol that is widely used for various purposes.

It is contemplated that sufiicient sealant will be applied forcefully to cause the sealant to extrude through the gap 52 and thereby form an extruded plug 55 in the gap as shown in FIG. 8. It may be seen in FIG. 8 that the extruded plug 55 is below the level of the lower surface of the tear strip 15 and therefore is not in the path of movement of the peeling movement of the tear strip when the tear strip is severed from the container. It is apparent in FIG. 6 that the extrusion scoring 14a provides a substantially wide-r groove than the conventional scoring 14b and thus provides a substantial area in which the sealant is bonded to the sheet metal to resist any tendency for the confined fluid pressure in the container to rupture the sealant.

After the sealant is applied in the manner shown in FIGS. 6 and 9, the tab 16 is positioned on the can top over the sealant 54 with the rivet 18 extending through an aperture 56 in the tab as shown in FIG. 4. The hollow rivet 18a of the preliminary rivet configuration is then headed into permanent engagement with the tab 16 by suitable die means (not shown). Preferably, the hollow rivet is headed by a well known operation which squeezes the transverse end wall 39 of the hollow rivet and thereby extrudes the metal of the transverse end wall radially to give the hollow rivet the final configuration 18 shown in FIG. 5.

It can be seen in FIG. 5 that the heading operation produces a circumferential bead 60 which overhangs the tab 16 in positive overlapping engagement with the rim of the aperture 56 of the tab. Thus the overhanging bead 60 of the rivet clamps the tab 16 firmly against the can top to confine the sealant 54 in the groove of the extruded scoring 1411.

It is contemplated that a slight excess of sealant will be placed in the scored groove as indicated in FIG. 9 where the sealant extends slightly above the level of the top of the groove. By virtue of the slight excess of sealant, the final clamping action of the rivet against the tab creates pressure against the sealant to bring the sealant into intimate contact with the sheet metal and to force 7 the sealant into and through the gap 52 to form the sealing plug 55 at the pre-sheared zone of the grooved scoring. It is to be further noted that the confinement of the sealant under compression in the groove of the scoring strengthens the exceedingly thin portion of the residual web 45 of the can wall against any tendency of the fluid pressure inside the can to cause the residual web to be displaced or distorted.

Because of the presence of the pre-sheared zone 50 at the point of initial application of the severance force by the tab 16 it is not necessary to exert initial severance force of peak magnitude to puncture the sheet metal and the fact that the residual web 45 is exceedingly thin in both directions from the pre-sheared zone facilitates the severance of the sheet metal in both directions from the pre-sheared zone. The reduced resistance of the tapered residual web is especially advantageous because early in the severance operation the tab 16 is at a relatively low angle of inclination relative to the can top. As the tab is raised to a higher angle it becomes easy for the user to increase the applied force as the thicker portions of the residual web 45 are encountered.

My description in specific detail of the preferred embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In an easy opening container having a wall made of sheet material, wherein the wall is weakened along a line to define a tear strip and a tab is provided for manual severance of the tear strip, the tab is provided for manual severance of the tear strip, the tab being attached to the leading end of the tear strip by a hollow rivet formed in the tear strip and extending through an aperture in the tab with a peripheral bead of the rivet overlapping thetab-adjacent the aperture, the improved comprising:

the sheet material being incised at a point on the weakened line at the leading end of the tear strip to facilitate initial severance of the tear strip; and

a layer of sealant material being bonded to the sheet material and covering and sealing the incision, said point at which the sheet material is incised being overlapped by said portion of the tab that is overlapped by the peripheral head of the rivet. 2. In an easy opening container having a wall made of sheet material, wherein the wall is weakened by a groove in the sheet material along a line to define a tear strip, the sheet material being reduced in thickness to a thin residual web at the bottom of the groove and a tab is attached to the leading end of the tear strip for manual severance of the tear strip, the improvement comprising: the sheet material being incised at a point on the residual web at the leading end of the tear strip to facilitate initiating severance of the tear strip,

the residual web tapering in thickness towards the incision in both directions along the groove; and

a layer of sealant material being bonded to the sheet material and covering and sealing the incision.

3. In an easy opening container having a wall made of sheet material, wherein the wall is weakened by a groove, the groove forming a thin residual. web of material defining a tear strip and a tab is attached to the tear strip to serve as a handle for removing the tear strip, the improvement comprising:

the sheet material being cut at a point in said web at the leading end of the tear strip to facilitate initiating severance of the tear strip; sealant occupying the groove in the region of the cut to seal the cut; and a solid extruded rib being formed along the residual web in the region of the cut on the side of the groove away from the tear strip to stiffen the sheet material adjacent the web to facilitate initiation of severance of the tear strip. v 4. In an easy opening container having a wall of sheet material, the combination of:

a groove in the outer face of the sheet material forming a score line defining a tear strip, said groove forming a thin residual Web of the sheet material on the tear strip side of the groove along which the leading end of the tear strip may be severed from the container wall,

, said residual web being cut longitudinally along a line of minute length to provide a starting point for severance of the leading end of the tear strip with the portions of the Web on the opposite sides of the line of cut offset from each other to form a gap in the sheet material;

the sheet material displaced by the formation of the groove forming an extruded rib protruding from the inner face of the sheet material along the portion of the groove that defines the leading end of the tear strip;

said rib being outside of the area of the tear strip that is defined by the residual web thereby to resist flexure of the sheet material adjacent the tear strip to fa cilitate severance of the tear strip; and

sealant material occupying said groove and extending into said gap to seal the gap.

5. A'combination as set forth in claim 4 in which the residual web along the side of the line of cut that is away from the tear strip is offset inwardly of the container to place the gap at a lower level than the underside of the tear strip to avoid the necessity of shearing the sealant at the gap in the operation of severing the tear strip.

6. In an easy opening container having a wall of sheet material, the combination of:

a groove in the outer face of the sheet material forming a score line defining a tear strip, 'said groove forming a thin residual web of the sheet material on the tear strip side of the groove along which the leading end of the tear strip may be severed from the container Wall, said residual'web being punctured to provide a starting point for severance of the leading end of the tear strip; I 7 the material displaced by the formation of the groove forming an extruded rib protruding from the inner face of the sheet material along the portion of the groove that defines the leading end of the tear strip;

said rib being outside of the area of the tear strip that is defined by the residual web thereby to resist flexure of the sheet material adjacent the tear strip to facilitate severance of the tear strip;

sealant material occupying said groove at the puncture to seal the puncture; and

a tab attached to the leading end of the tear strip to serve as a handle for manipulating the tear strip, a portion of the tab overlying and protecting the sealant in the groove.

7. A combination as set forth in claim 6 in which the tab is attached to the tear strip by a hollow rivet formed in the tear strip and extending through an aperture in the tab with a peripheral bead of the rivet overlapping said portion of the tab directly above the puncture.

8. In a me hod of fabricating an easy opening container wherein a sheet metal wall of the container is weakened along a line to form a thin residual web defining a tear strip, the improvement comprising:

scoring the sheet metal along the line to form a groove providing the residual web;

in the same operation, puncturing the web adjacent the leading end of the tear strip to provide a starting point for severance of the leading end; and

applying sealant along the line of scoring to seal the puncture in the web.

9. In a method of fabricating an easy opening container wherein a sheet metal wall of the container is scored to form a groove providing a thin residual web defining a tear strip, the improvement comprising:

scoring the sheet metal to form the groove and residual web and, in the same operation, shearing the web longitudinally along a line of minute length adjacent the leading end of the tear strip to provide a starting point for severance of the leading end; additionally in the same operation offsetting inwardly of the container the residual web on the side of the line of shear that is away from the tear strip to form a gap at the line of shear; and applying sealant along the line of shear to seal the gap. 10. An improvement in the method of fabricating an easy opening container as set forth in claim 9, in which the sealant is applied to completely span the interior of the groove; and

which includes the further step of attaching a tab to the tear strip in a position to overlie the sealant and confine the sealant in the groove.

11. In a method of fabricating an easy opening container wherein a sheet metal wall of the container is scored to form a groove providing a thin residual web defining a tear strip, the improvement comprising:

scoring the sheet metal by displacing the sheet metal to form the groove and in the region of the leading end of the tear strip simultaneously forming an inwardly projecting extruded rib extending along the line of scoring outside of the area defined by the I residual web; shearing the web longitudinally along a line of minute length adjacent the leading end of the tear strip to provide a starting point for severance of the leading end; offsetting inwardly of the container the residual web on the side of the line of shear that is away from the tear strip to form a gap at the line of shear; and applying sealant along the line of shear to seal the gap. 12. A method as set forth in claim 11 which includes the further improvement of forming the groove with progressive increase in depth along the groove towards the region of the line of shear for progressive thinning of the residual web towards that region to reduce the amount of manual force required to extend the shearing of the metal beyond the ends of the line of shear.

13. In a method of fabricating an easy opening con- .tainer wherein a sheet metal wall of the container is scored to form a groove providing a thin residual web defining a tear strip, the improvement comprising:

scoring the metal to form the groove and residual web; puncturing the residual web adjacent the leading end of the tear strip to provide a starting point for severance of the tear strip; placing sealant in the groove in the region of the puncture in an amount in excess of the amount required to fill the groove transversely; and placing a tab in position across the seal-ant and pressing the tab against the excess sealant to place the sealant under pressure, and anchoring the tab to the tear strip to keep the tab in pressure contact with the sealant as well as to permit the tab to serve as a handle for manipulation of the tear strip.

References Cited UNITED STATES PATENTS 3,283,945 11/1966 Close 22054 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner. 

1. IN AN EASY OPENING CONTAINER HAVING A WALL MADE OF SHEET MATERIAL, WHEREIN THE WALL IS WEAKENED ALONG A LINE TO DEFINE A TEAR STRIP AND A TAB IS PROVIDED FOR MANUAL SEVERANCE OF THE TEAR STRIP, THE TAB IS PROVIDED FOR MANUAL SEVERANCE OF THE TEAR STRIP, THE TAB BEING ATTACHED TO THE LEADING END OF THE TEAR STRIP BY A HOLLOW RIVET FORMED IN THE TEAR STRIP AND EXTENDING THROUGH AN APERTURE IN THE TAB WITH A PERIPHERAL BEAD OF THE RIVET OVERLAPPING THE TAB ADJACENT THE APERTURE, THE IMPROVED COMPRISING: THE SHEET MATERIAL BEING INCISED AT A POINT ON THE WEAKENED LINE AT THE LEADING END OF THE TEAR STRIP TO FACILITATE INITIAL SEVERANCE OF THE TEAR STRIP; AND A LAYER OF SEALANT MATERIAL BEING BONDED TO THE SHEET MATERIAL AND COVERING AND SEALING THE INCISION, SAID POINT AT WHICH THE SHEET MATERIAL IS INCISED BEING OVERLAPPED BY SAID PORTION OF THE TAB THAT IS OVERLAPPED BY THE PERIPHERAL BEAD OF THE RIVET. 